(1) Field of the Invention
Optical hydrophones are being developed to be deployed as acoustic sensors. An interferometric system has been devised that utilizes optical hydrophones for deployment at sea.
(2) Description of the Prior Art
In a typical interferometric system a sensor hydrophone is exposed to the acoustic pressure medium and a reference leg is isolated from the acoustic pressure medium. Both hydrophone and reference leg are constructed so that if the acoustic pressure medium were removed from the sensor hydrophone then both the sensor hydrophone and reference leg would have identical outputs. It is due to the fact that in an interferometric system the output signal of the sensor hydrophone differs from that of the reference leg that enables the system to operate. The sensor hydrophone develops a signal from the acoustic pressure medium that the reference leg does not see. This enables an output to be developed once the signals from the sensor hydrophone and reference leg are recombined.